Prevalence of meticillin-resistant Staphylococcus pseudintermedius (MRSP) from skin and carriage sites of dogs after treatment of their meticillin-resistant or meticillin-sensitive staphylococcal pyoderma

Minimum inhibitory and bactericidal/fungicidal concentration of commercially available products containing essential oils, zinc gluconate, or 4% chlorhexidine for Malassezia pachydermatis, Pseudomonas aeruginosa, and multi-drug resistant Staphylococcus pseudintermedius canine clinical isolates

Skin infections are common complications in both humans and animals. Because of the increased incidence of multi-drug resistant (MDR) skin infections, essential oils have been suggested as potential alternatives to the classic antimicrobials. The goal of this study was to evaluate the minimum inhibitory and bactericidal/fungicidal concentrations (MIC and MBC/MFC) of commercially available products containing essential oils, zinc gluconate, or 4% chlorhexidine. Microbroth dilution technique was performed on clinical isolates of MDR Staphylococcus pseudintermedius (MDR-SP; n = 10), Pseudomonas aeruginosa (PA; n = 10), and Malassezia pachydermatis (MP; n = 10). For MDR-SP, essential oil-containing products showed median MICs of 1:240 and 1:320. The chlorhexidine shampoo had a MIC of 1:128,000 (0.312 µg/mL), whereas zinc gluconate products had median MICs of 1:320 and 1:160. Three essential oil-containing shampoos (MBC 1:40), the zinc gluconate (MBC 1:40), and the chlorhexidine (MBC 1:64,000 [0.625 µg/mL]) reached an MBC. For PA, essential oil-containing products showed median MICs of 1:30 and 1:80. The zinc-gluconate products had a median MIC of 1:160, whereas the chlorhexidine shampoo had a median MIC of 1:4,000 (10 µg/mL). Only the zinc-gluconate products (MBC 1:80) and the chlorhexidine shampoo (MBC 1:2,000 [20 µg/mL]) reached an MBC. For MP, essential oil-containing and zinc-gluconate products showed lower median MICs (1:4,800 and 7,200) for shampoos compared with other formulations (1:160 and 1:320), whereas the chlorhexidine shampoo had a median MIC of 1:80,000 (0.5 µg/mL). These results suggest that natural topical compounds can be an effective alternative to treat skin infections in companion animals. Further in vivo studies are needed to clinically confirm this study's results.

Not just in man's best friend: A review of Staphylococcus pseudintermedius host range and human zoonosis

Staphylococcus pseudintermedius is one species in the commensal staphylococcal population in dogs. While it is commonly carried on healthy companion dogs it is also an opportunistic pathogen associated with a range of skin, ear, wound and other infections. While adapted to dogs, it is not restricted to them, and we have reviewed its host range, including increasing reports of human colonisation and infections. Despite its association with pet dogs, S. pseudintermedius is found widely in animals, covering companion, livestock and free-living species of birds and mammals. Human infections, typically in immunocompromised individuals, are increasingly being recognised, in part due to improved diagnosis. Colonisation, infection, and antimicrobial resistance, including frequent multidrug resistance, among S. pseudintermedius isolates represent important One Health challenges.

Efficacy of Short Novel Antimicrobial Peptides in a Mouse Model of Staphylococcus pseudintermedius Skin Infection

As the clinical application of antibiotics for bacterial skin infections in companion animals becomes increasingly prevalent, the issue of bacterial resistance has become more pronounced. Antimicrobial peptides, as a novel alternative to traditional antibiotics, have garnered widespread attention. In our study, synthetic peptides ADD-A and CBD3-ABU were tested against Staphylococcus pseudintermedius skin infections in KM mice. ADD-A was applied topically and through intraperitoneal injection, compared with control groups and treatments including CBD3-ABU, ampicillin sodium, and saline. Wound contraction, bacterial counts and histology were assessed on days 3 and 11 post-infection. ADD-A and ampicillin treatments significantly outperformed saline in wound healing (p < 0.0001 and p < 0.001, respectively). ADD-A also showed a markedly lower bacterial count than ampicillin (p < 0.0001). Histologically, ADD-A-applied wounds had better epidermal continuity and a thicker epidermis than normal, with restored follicles and sebaceous glands. ADD-A's effectiveness suggests it as a potential alternative to antibiotics for treating skin infections in animals.

Exploring Efflux as a Mechanism of Reduced Susceptibility towards Biocides and Fluoroquinolones in Staphylococcus pseudintermedius

Staphylococcus pseudintermedius is the main bacterial cause of skin and soft tissue infections (SSTIs) in companion animals, particularly dogs. The emergence of methicillin-resistant S. pseudintermedius (MRSP) strains, frequently with multidrug resistance phenotypes is a public health concern. This study aimed to evaluate efflux, a resistance mechanism still poorly characterized in S. pseudintermedius, as a contributor to biocide and fluoroquinolone resistance. Susceptibility to the efflux pump substrates ethidium bromide (EtBr), tetraphenylphosphonium bromide (TPP) and ciprofloxacin (CIP) was evaluated by minimum inhibitory concentration (MIC) determination for 155 SSTIs-related S. pseudintermedius in companion animals. EtBr and TPP MIC distributions were analyzed to estimate cut-off (COWT) values. The effect of the efflux inhibitors (EIs) thioridazine and verapamil was assessed upon MICs and fluorometric EtBr accumulation assays, performed with/without glucose and/or EIs. This approach detected a non-wild type population towards TPP with increased efflux, showed to be strain-specific and glucose-dependent. Resistance to fluoroquinolones was mainly linked to target gene mutations, yet a contribution of efflux on CIP resistance levels could not be ruled out. In sum, this study highlights the relevance of efflux-mediated resistance in clinical S. pseudintermedius, particularly to biocides, and provides a methodological basis for further studies on the efflux activity on this important pathogen of companion animals.

Nasal microbiota profiles in shelter dogs with dermatological conditions carrying methicillin-resistant and methicillin-sensitive Staphylococcus species

Dermatological conditions may be complicated by Staphylococcus spp. infections influencing skin and nasal microbiota. We investigated the associations between the resident nasal microbiota of shelter dogs with and without dermatological conditions carrying methicillin-resistant and -sensitive Staphylococcus spp. Nasal sampling of 16 dogs with and 52 without dermatological conditions were performed upon shelter admission (baseline), and then bi-weekly until discharge (follow-up). All samples were cultured for Staphylococcus spp., while 52 samples underwent microbiota analysis. Two elastic net logistic regression (ENR) models (Model 1-baseline samples; Model 2-follow-up samples) were developed to identify predictive associations between dermatological conditions and the variables: signalment, antimicrobial treatment, and nasal microbial genera. Follow-up nasal samples of dogs with dermatological conditions had decreased microbiota diversity and abundance compared to dogs without dermatological conditions. Our ENR models identified predictive differences in signalment and nasal microbial genera between baseline and follow-up samples. Co-occurrence networks showed nasal microbial genera were more dissimilar when comparing dogs with and without dermatological conditions at follow-up. Overall, this study is the first to investigate Staphylococcus spp. carriage effects on nasal microbial genera in a canine animal shelter population, and ultimately reveals the importance of investigating decolonisation and probiotic therapies for restoring nasal microbiota.

Prevalence and multidrug-resistant profile of methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus pseudintermedius in dogs, cats, and pet owners in Malaysia

Background and Aim

Staphylococcus aureus and Staphylococcus pseudintermedius are widespread skin and mucous membrane colonizers and may cause opportunistic infections in humans and animals. This study aimed to identify and characterize methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. pseudintermedius (MRSP) isolates from domestic and stray dogs and cats and pet owners in Malaysia using molecular epidemiology and antimicrobial profiling.

Materials and Methods

Three hundred and fifty oral and nasal swabs were taken from pet and stray dogs and cats and pet owners; all samples were subjected to culture and biochemical tests and polymerase chain reaction; the selected isolates were put through disk diffusion test and multilocus sequence typing.

Results

One S. aureus isolate and three S. pseudintermedius isolates were identified as MRSA and MRSP, respectively, of which the MRSA isolate and one of the MRSP isolates showed multidrug resistance and the remaining two MRSP isolates were resistant to one or two antimicrobials. Multilocus sequence typing showed that the MRSA isolate belongs to clonal complex (CC) 789, while for the MRSP isolates, two were in CC45 and one was a singleton.

Conclusion

This study is the first study in Malaysia to perform molecular characterization of MRSP isolated from pet dogs and cats and pet owners. The outcomes of this study reveal that even healthy pet dogs and cats and their owners can be carriers of drug-resistant staphylococci, highlighting the role of pets and pet owners as carriers of MRSA and MRSP in Malaysia.

Prevalence and multidrug-resistant profile of methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus pseudintermedius in dogs, cats, and pet owners in Malaysia

Background and Aim: Staphylococcus aureus and Staphylococcus pseudintermedius are widespread skin and mucous membrane colonizers and may cause opportunistic infections in humans and animals. This study aimed to identify and characterize methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. pseudintermedius (MRSP) isolates from domestic and stray dogs and cats and pet owners in Malaysia using molecular epidemiology and antimicrobial profiling. Materials and Methods: Three hundred and fifty oral and nasal swabs were taken from pet and stray dogs and cats and pet owners; all samples were subjected to culture and biochemical tests and polymerase chain reaction; the selected isolates were put through disk diffusion test and multilocus sequence typing. Results: One S. aureus isolate and three S. pseudintermedius isolates were identified as MRSA and MRSP, respectively, of which the MRSA isolate and one of the MRSP isolates showed multidrug resistance and the remaining two MRSP isolates were resistant to one or two antimicrobials. Multilocus sequence typing showed that the MRSA isolate belongs to clonal complex (CC) 789, while for the MRSP isolates, two were in CC45 and one was a singleton. Conclusion: This study is the first study in Malaysia to perform molecular characterization of MRSP isolated from pet dogs and cats and pet owners. The outcomes of this study reveal that even healthy pet dogs and cats and their owners can be carriers of drug-resistant staphylococci, highlighting the role of pets and pet owners as carriers of MRSA and MRSP in Malaysia. Keywords: antimicrobial resistance, antimicrobial susceptibility testing, methicillin resistance, multilocus sequence typing, public health, zoonotic infections.

Prevalence of multidrug-resistant coagulase-positive staphylococci in canine and feline dermatological patients over a 10-year period: a retrospective study

Coagulase-positive staphylococci (CPS) are common cutaneous pathogens often requiring multiple courses of antibiotics, which may facilitate selection for methicillin-resistant (MR) and/or multidrug-resistant (MDR) strains. To determine the prevalence of canine and feline MR/MDR CPS associated with skin diseases, medical records were retrospectively searched from April 2010 to April 2020. Pets with at least one positive culture for CPS were selected. Age, sex, antimicrobial sensitivity, previous history of antimicrobial/immunomodulatory medications and methicillin resistance/multidrug resistance status were recorded. Staphylococcus pseudintermedius (SP) (575/748) and Staphylococcus schleiferi (SS) (159/748) in dogs, and Staphylococcus aureus (12/22) in cats, were the most common CPS isolated. Three hundred and twenty-three out of 575 isolates were MR-SP (56.2 %), 304/575 were MDR-SP (52.8 %), 100/159 were MR-SS (62.9 %) and 71/159 were MDR-SS (44.6 %). A trend analysis showed a significant increase of resistance to oxacillin and chloramphenicol for S. pseudintermedius (r=0.86, 0.8; P=0.0007, 0.0034, respectively). Major risk factors for MDR-SP included oxacillin resistance (OR: 3; 95 % CI: 1.4-6.5; P=0.0044), positivity for PBP2a (OR: 2.3; 95 % CI: 1-5; P=0.031) and use of antibiotics in the previous year (OR: 2.8; 95 % CI: 1.3-5.8; P=0.0071). Oxacillin resistance was identified as a major risk factor for MDR-SS (OR: 8.8; 95 % CI: 3.6-21.1; P<0.0001). These results confirmed the widespread presence of MR/MDR CPS in referred dermatological patients. Judicious antibiotic use, surveillance for MR/MDR infections and consideration of alternative therapies are crucial in mitigating the development of resistant strains.

Fluorescent Light Energy in the Management of Multi Drug Resistant Canine Pyoderma: A Prospective Exploratory Study

The increase in prevalence of staphylococcal antimicrobial resistance has been also associated with pyoderma in dogs, and prolonged antibiotic treatment, as often needed in severe cases of pyoderma, has been related to influencing possible development of multidrug resistance (MDR). Fluorescent light energy (FLE) has been indicated to improve pyoderma lesions as adjunct therapy to systemic antibiotics. In the present study, we evaluated the effect of FLE on clinical signs of MDR canine deep pyoderma (CDP) and interdigital furunculosis (CIF) when administered as solely management. Sixteen client-owned dogs affected by CIF (five dogs) and CDP (eleven dogs) were scored using a dedicated scoring system and received a single FLE applications twice weekly, until clinical resolution was achieved. Mean time to achieve complete resolution was 5.20 ± 3.56 weeks (median 3 weeks) for CIF cases and 4.18 ± 1.47 weeks (median 4 weeks) for CDP ones. FLE shows promise as an aid to managing clinical signs while reducing reliance on antibiotics for MDR CDP and CIF. In this study, FLE was responsible for the decrease in lesion scores and resolution of MDR pyoderma infection without any adjunct therapy, having a potential useful role to play in antibiotic stewardship programs, efficiently promoting complete clinical resolution of MDR lesions while optimizing the use of antibiotics.

Efficacy of a quaternary ammonium compound in reducing coagulase-positive staphylococcal colony counts in veterinary dermatology exam rooms following two cleaning instruction protocols

BACKGROUND

Nosocomial meticillin-resistant (MR) staphylococcal infections are of global concern. Veterinary dermatology exam room surfaces may be a reservoir given the commonness of staphylococcal pyoderma.

HYPOTHESIS/OBJECTIVES

First, efficacy of exam room surface decontamination using a quaternary ammonium compound was assessed after use of two different cleaning instruction protocols. Second, coagulase-positive staphylococcal (CoPS) colony counts were assessed after use of rooms by dogs with pyoderma, and then after cleaning and disinfection.

METHODS AND MATERIALS

In Part I, 10 room surfaces were tagged with a discreet fluorescent dye, Glo Germ, to assess the efficacy of surface cleaning between two Virex II 256-based cleaning protocols. In Part II, CoPS colonies were quantified via 3M Staph Express System. Ten standardised room surfaces were sampled after use by a dog with staphylococcal pyoderma, and immediately after a detailed cleaning and disinfection protocol.

RESULTS

A total of 24 of 100 and 81 of 100 surfaces were completely cleaned by the general and detailed protocols, respectively. The mean number of surfaces adequately cleaned was higher with the detailed protocol (P = 0.003). The detailed protocol reduced CoPS colony counts of eight surfaces (P < 0.01), and not chairs (P = 0.055). No CoPS were isolated from the exam table under a table mat.

CONCLUSIONS AND CLINICAL RELEVANCE

Detailed exam room cleaning and disinfection protocols are recommended to minimise contamination of veterinary exam room surfaces with staphylococci. The appropriate disinfection of chairs necessitates further study.

Prevalence of coagulase-positive methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius in dogs in Bangladesh

Background

The emergence of methicillin‐resistant Staphylococcus aureus (MRSA) and methicillin‐resistant Staphylococcus pseudintermedius (MRSP) have a significant health impact on people with direct or supportive occupations in veterinary medicine including veterinarians, animal handlers, laboratory personnel and pet owners.

Objectives

This cross‐sectional survey was conducted to determine the prevalence of and risk factors for S. aureus, S. pseudintermedius, MRSA and MRSP in dogs in Bangladesh.

Methods

A total of 358 swab samples were collected from different body sites of 150 dogs attending a university teaching veterinary hospital between January and June 2018. Standard bacteriological procedures were followed to isolate Staphylococcus, and identification was confirmed to the species level by PCR to detect the nuc gene. MRSA and MRSP were confirmed by the presence of the mecA gene.

Results

The prevalence of coagulase‐positive S. aureus and S. pseudintermedius in dogs were 16% and 45.3%, respectively. S. aureus and S. pseudintermedius isolates displayed the highest resistance against nalidixic acid (95.2% and 91%, respectively) and erythromycin (89.3% and 84.7%, respectively). Notably, all the staphylococcal isolates showed resistance to ≥3 antimicrobial classes. The prevalence of MRSA and MRSP in dogs was 8.7% and 6%, respectively. Multivariable logistic regression analysis identified the following variables as risk factors for MRSA colonisation in dogs: dogs with dermatitis (odds ratio [OR], 12.24, 95% CI: 3.12–57.33; p < 0.001) and history of antibiotic use (OR 8.73, 95% CI: 2.23–43.10; p < 0.001). Presence of otitis (OR 14.22; 95% CI: 1.64–103.58; p = 0.008) and oral lesions (OR 9.48, 95% CI: 1.14–64.82; p = 0.002) were identified as the significant risk factors for the carriage of MRSP.

Conclusions

The circulation of multidrug‐resistant S. aureus and S. pseudintermedius is a serious concern to dogs and humans. To our knowledge, this is the first report of S. pseudintermedius and MRSP affecting dogs in Bangladesh.

Effect of topical antimicrobial therapy and household cleaning on meticillin-resistant Staphylococcus pseudintermedius carriage in dogs

BACKGROUND

Meticillin-resistant Staphylococcus pseudintermedius (MRSP) is a multidrug-resistant canine pathogen with a low zoonotic potential. This study investigated MRSP carriage and clearance through topical antimicrobial therapy and household cleaning in dogs recovered from MRSP infection.

METHODS

Dogs were swabbed for MRSP carriage; household contamination was assessed using contact plates. Carrier dogs were allocated randomly to receive topical fusidic acid and chlorhexidine/miconazole treatment combined with owners implementing a household hygiene protocol (H&T) or implementation of hygiene alone (H) over three weeks. Carriage-negative dogs were monitored monthly. The relatedness of isolates over time was investigated by pulsed-field gel electrophoresis (PFGE).

RESULTS

At inclusion, MRSP carriage was confirmed in 31/46 (67.4%) index dogs and 16/24 (66.7%) contact dogs, and contamination was found in 18/40 (45%) environments. In dogs completing all cycles, interventions cleared carriage in 5/9 (55.6%) dogs in group H&T and 2/6 (33.3%) in group H. Environmental contamination was infrequent but associated with carrier dogs (p = 0.047). Monthly monitoring of initially negative dogs showed intermittent carriage in 9/14 dogs. PFGE-concordance was found among all 34 MRSP isolated from eight index dogs over time.

CONCLUSION

MRSP carriage was common in dogs after recovery from infection. Topical antimicrobial therapy temporarily eliminated carriage but recurrence was frequent. Management efforts must include the prevention of recurrent infections and hygiene.

Determination of the frequency, species distribution and antimicrobial resistance of staphylococci isolated from dogs and their owners in Trinidad

The close contact between humans and their dogs can lead to the commingling of staphylococci and the exchange of mobile genetic elements encoding antimicrobial resistance. The objectives of this study were to determine the species distribution and antimicrobial resistance patterns of staphylococci colonizing canine pets and their owners in Trinidad. Staphylococci were isolated from canine pets and their owners and identified using MALDI-TOF mass spectrometry. Antimicrobial susceptibilities were determined using the Kirby-Bauer disc diffusion method against seven classes of antimicrobial agents. A total of 440 staphylococci were isolated from 112 canine pets and their owners, 53.4% were from canine pets and 46.6% were from owners. Twenty-four species were detected, of which, most isolates (32.5%) belonged to the Staphylococcus intermedius group (SIG). S. sciuri was the most common species of coagulase-negative staphylococci (CoNS) comprising 22.3% of all isolates. Antimicrobial resistance was highest against commonly used antimicrobials, such as penicillin (51.4%), tetracycline (26.1%) and trimethoprim/sulfamethoxazole (18.6%). These antimicrobials also comprised the most common multidrug resistance (MDR) combination. Overall, 19.1% of isolates displayed multidrug resistance. No methicillin-resistant Staphylococcus aureus (MRSA) isolates were detected. However, methicillin resistance was detected in 13.3% and 15.1% of coagulase-positive staphylococci (CoPS) and the CoNS+CoVS (combined CoNS and coagulase-variable staphylococci) group respectively. The presence of methicillin-resistant staphylococci is worrisome because there is the potential for the transfer of these strains between dogs and humans. These strains may act as a reservoir of resistance genes.

Phenotypic and Molecular Traits of Staphylococcus coagulans Associated with Canine Skin Infections in Portugal

Staphylococcus coagulans is among the three most frequent pathogens of canine pyoderma. Yet, studies on this species are scarce. Twenty-seven S. coagulans and one S. schleiferi, corresponding to all pyoderma-related isolations from these two species at two veterinary laboratories in Lisbon, Portugal, between 1999 and 2018 (Lab 1) or 2018 (Lab 2), were analyzed. Isolates were identified by the analysis of the nuc gene and urease production. Antibiotic susceptibility towards 27 antibiotics was evaluated by disk diffusion. Fourteen antibiotic resistance genes were screened by PCR. Isolates were typed by SmaI-PFGE. Two S. coagulans isolates (2/27, 7.4%) were methicillin-resistant (MRSC, mecA+) and four (4/27, 14.8%) displayed a multidrug-resistant (MDR) phenotype. We observed resistance to penicillin (17/27, 63.0%), fluoroquinolones (11/27, 40.7%), erythromycin and clindamycin (3/27, 11.1%), fusidic acid (3/27, 11.1%) and tetracycline (1/27, 3.7%). The blaZ and erm(B) genes were carried by 16 and 1 isolates resistant to penicillin and erythromycin/clindamycin, respectively. Only three S. coagulans carried plasmids. The single S. schleiferi isolate presented an MDR phenotype. SmaI-PFGE revealed a limited genetic diversity of S. coagulans, with a predominant lineage present from 2001 to 2018. This study describes the first MRSC causing canine infection in Portugal and reveals a high burden of antimicrobial resistance, with the emergence of MDR phenotypes within the main lineages.

Molecular Epidemiology of Clinical and Colonizing Methicillin-Resistant Staphylococcus Isolates in Companion Animals

In this study, we aimed to investigate the molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) clinical and colonizing isolates of dogs and cats to profile contributing factors associated with their isolation. Nasal and rectal samples were collected from dogs and cats between 2015 and 2017 to identify colonizing isolates. Clinical isolates collected between 2003 and 2016 were retrieved from a Queensland university veterinary diagnostic laboratory. All isolates were identified using standard microbiological and molecular methods and were characterized by whole genome sequencing. Phylogenetic relationships and differences in epidemiological factors were investigated. Seventy-two MRSP isolates out of 1,460 colonizing samples and nine MRSP clinical isolates were identified. No MRSA was isolated. ST496 and ST749 were the most commonly isolated sequence types with different SCCmec types. ST496 clones spread both along the coast and more inland where ST749 was more centered in Brisbane. The resistance and virulence factors differed significantly between the two sequence types. ST496 colonizing and clinical isolates were similarly multidrug resistant. The virulence genes of ST749 colonizing and clinical isolates were similar as both contained the gene nanB for sialidase. There were no differences in the individual and clinical factors between predominant sequence types. High levels of antimicrobial resistance occurred in the majority of isolates, which is of potential concern to human and veterinary health. The phylogenetic clustering of isolates from this study and others previously identified in countries, particularly New Zealand, with which Australia has high volume of pet movements could suggest the importation of clones, which needs further investigation.

Staphylococcus lugdunensis: a Skin Commensal with Invasive Pathogenic Potential

Staphylococcus lugdunensis is a species of coagulase-negative staphylococcus (CoNS) that causes serious infections in humans akin to those of S. aureus It was often misidentified as S. aureus, but this has been rectified by recent routine use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in diagnostic laboratories. It encodes a diverse array of virulence factors for adhesion, cytotoxicity, and innate immune evasion, but these are less diverse than those encoded by S. aureus It expresses an iron-regulated surface determinant (Isd) system combined with a novel energy-coupling factor (ECF) mechanism for extracting heme from hemoproteins. Small cytolytic S. lugdunensis synergistic hemolysins (SLUSH), peptides related to phenol-soluble modulins of S. aureus, act synergistically with β-toxin to lyse erythrocytes. S. lugdunensis expresses a novel peptide antibiotic, lugdunin, that can influence the nasal and skin microbiota. Endovascular infections are initiated by bacterial adherence to fibrinogen promoted by a homologue of Staphylococcus aureus clumping factor A and to von Willebrand factor on damaged endothelium by an uncharacterized mechanism. S. lugdunensis survives within mature phagolysosomes of macrophages without growing and is released only following apoptosis. This differs fundamentally from S. aureus, which actively grows and expresses bicomponent leukotoxins that cause membrane damage and could contribute to survival in the infected host. S. lugdunensis is being investigated as a probiotic to eradicate S. aureus from the nares of carriers. However, this is contraindicated by its innate virulence. Studies to obtain a deeper understanding of S. lugdunensis colonization, virulence, and microbiome interactions are therefore warranted.

Antimicrobial agent use in small animals what are the prescribing practices, use of PK-PD principles, and extralabel use in the United States?

In this review, the availability and deficiencies of current antimicrobial agents for companion animals in the United States are described. Although several active agents are FDA-approved for small animals, there are many unmet needs. These needs are greatest for cats, for the treatment of antibiotic drug-resistant infections, and to treat new or emerging pathogens that were not considered on older labels. The older agents approved before 1997 are often outdated, unavailable, or have inaccurate labeling. Subsequently, veterinarians treat dogs and cats with many unapproved antimicrobial agents that are licensed for human use. Although these drugs may be effective, there are also concerns that this use can produce drug-resistant bacteria that may be a public health risk. Although this concern is real, there is also evidence that any antimicrobial use in small animals can produce resistant fecal bacteria and stewardship principles should aim at reducing any unnecessary antibiotic use. This could be accomplished by avoiding some of the older, ineffective, or outdated agents described in this paper. There is a need for incentives to approve new agents that will be more appropriate for treating infections in companion animals without increasing the risk of drug-resistant bacteria that could potentially be transferred to humans and the environment and create a public health risk.

Antimicrobial prophylaxis is considered sufficient to preserve an acceptable surgical site infection rate in clean orthopaedic and neurosurgeries in dogs

Background

Surgical site infections (SSI) are associated with increased morbidity and mortality. To lower the incidence of SSI, antimicrobial prophylaxis is given 30–60 min before certain types of surgeries in both human and veterinary patients. However, due to the increasing concern of antimicrobial resistance, the benefit of antimicrobial prophylaxis in clean orthopaedic and neurosurgeries warrants investigation. The aims of this retrospective cross-sectional study were to review the rate of SSI and evaluate the compliance with antimicrobial guidelines in dogs at a veterinary teaching hospital in 2012–2016. In addition, possible risk factors for SSI were assessed.

Results

Nearly all dogs (377/406; 92.9%) received antimicrobial prophylaxis. Twenty-nine dogs (7.1%) did not receive any antimicrobials and only four (1.1%) received postoperative antimicrobials. The compliance with in-house and national protocols was excellent regarding the choice of prophylactic antimicrobial (cefazolin), but there was room for improvement in the timing of prophylaxis administration. Follow-up data was available for 89.4% (363/406) of the dogs. Mean follow-up time was 464 days (range: 3–2600 days). The overall SSI rate was 6.3%: in orthopaedic surgeries it was 6.7%, and in neurosurgeries it was 4.2%. The lowest SSI rates (0%) were seen in extracapsular repair of cranial cruciate ligament rupture, ulnar ostectomy, femoral head and neck excision, arthrotomy and coxofemoral luxation repair. The highest SSI rate (25.0%) was seen in arthrodesis. Omission of antimicrobials did not increase the risk for SSI (P = 0.56; OR 1.7; CI_95% 0.4–5.0). Several risk factors for SSI were identified, including methicillin-resistant Staphylococcus pseudintermedius carriage (P = 0.02; OR 9.0; CI_95% 1.4–57.9) and higher body temperature (P = 0.03; OR 1.69; CI_95% 1.0–2.7; mean difference + 0.4 °C compared to dogs without SSI).

Conclusions

Antimicrobial prophylaxis without postoperative antimicrobials is sufficient to maintain the overall rate of SSI at a level similar to published data in canine clean orthopedic and neurosurgeries.

Efficacy of three disinfectant formulations and a hydrogen peroxide/silver fogging system on surfaces experimentally inoculated with meticillin-resistant Staphylococcus pseudintermedius

BACKGROUND

Effective environmental disinfection is necessary to prevent nosocomial infections from meticillin-resistant Staphylococcus pseudintermedius (MRSP). However, there are currently no commercial disinfectant sprays or fogging systems with label claims against MRSP.

HYPOTHESIS/OBJECTIVES

To evaluate the efficacy of a quaternary ammonium product (QAC), an accelerated hydrogen peroxide product (AHP), a hydrogen peroxide and silver product (HAL), and a hydrogen peroxide and silver fogging system (FOG) against MRSP.

METHODS AND MATERIALS

Sterile plastic surfaces inoculated with MRSP were treated with 200 µL of QAC, AHP or HAL for the recommended contact times. For FOG, inoculated samples were placed in eight positions within a sealed room before fogging for the recommended contact time. Post-treatment bacterial counts were compared to untreated positive controls. Sterile uninoculated surfaces served as negative controls.

RESULTS

Least-squares mean reduction (log₁₀ ) in colony forming units (cfu) was 3.55 log₁₀ for QAC (P < 0.0001), 3.60 log₁₀ for AHP (P < 0.0001), 1.66 log₁₀ for HAL (P < 0.0001) and 0.32 log₁₀ for FOG (P = 0.004). QAC, AHP and HAL reduced MRSP cfu by 99.97%, 99.98% and 97.81%, respectively. FOG reduced cfu by 52.14%.

CONCLUSIONS AND CLINICAL IMPORTANCE

QAC and AHP effectively disinfected surfaces inoculated with MRSP. Although HAL provided lower MRSP reduction, it may be considered clinically acceptable. FOG as a sole means of MRSP disinfection was not supported yet may have utility as an adjunctive disinfectant in clinical areas with bacterial densities lower than our experimental inoculum.

Appraisal of the Australian Veterinary Prescribing Guidelines for antimicrobial prophylaxis for surgery in dogs and cats

The Australian Veterinary Prescribing Guidelines for antimicrobial prophylaxis for surgery on dogs and cats are evidence-based guidelines for veterinary practitioners. Validation of these guidelines is necessary to ensure quality and implementability. Two validated tools, used for medical guideline appraisal, were chosen to assess the guidelines. The terminology from the GuideLine Implementability Appraisal (GLIA) and the Appraisal of Guidelines for Research and Evaluation version 2 (AGREE II) were adapted for use by veterinarians. A two-phase evaluation approach was conducted. In the first phase of the evaluation, the GLIA tool was used by two specialist veterinary surgeons in clinical practice. The results of this phase were then used to modify the guidelines. In the second phase, the AGREE II tool was used by 6 general practitioners and 6 specialists to appraise the guidelines. In phase 1, the specialist surgeons either agreed or strongly agreed that the guidelines were executable, decidable, valid and novel, and that the guidelines would fit within the process of care. The surgeons were neutral on flexibility and measurability. Additional clarity around one common surgical procedure was added to the guidelines, after which the surgeons agreed that the guidelines were sufficiently flexible. In phase 2, 12 veterinarians completed the assessment using the AGREE II tool. In all sections the scaled domain score was greater than 70%. The overall quality of the guidelines was given a global scaled score of 76%. This assessment has demonstrated that the guidelines for antimicrobial prophylaxis for companion animal surgery are valid and appear implementable.

In vitro Antimicrobial Activity of Robenidine, Ethylenediaminetetraacetic Acid and Polymyxin B Nonapeptide Against Important Human and Veterinary Pathogens

The emergence and global spread of antimicrobial resistance among bacterial pathogens demand alternative strategies to treat life-threatening infections. Combination drugs and repurposing of old compounds with known safety profiles that are not currently used in human medicine can address the problem of multidrug-resistant infections and promote antimicrobial stewardship in veterinary medicine. In this study, the antimicrobial activity of robenidine alone or in combination with ethylenediaminetetraacetic acid (EDTA) or polymyxin B nonapeptide (PMBN) against Gram-negative bacterial pathogens, including those associated with canine otitis externa and human skin and soft tissue infection, was evaluated in vitro using microdilution susceptibility testing and the checkerboard method. Fractional inhibitory concentration indices (FICIs) and dose reduction indices (DRI) of the combinations against tested isolates were determined. Robenidine alone was bactericidal against Acinetobacter baumannii [minimum inhibitory concentrations (MIC) mode = 8 μg/ml] and Acinetobacter calcoaceticus (MIC mode = 2 μg/ml). Against Acinetobacter spp., an additivity/indifference of the combination of robenidine/EDTA (0.53 > FICIs > 1.06) and a synergistic effect of the combination of robenidine/PMBN (0.5 < FICI) were obtained. DRIs of robenidine were significantly increased in the presence of both EDTA and PMBN from 2- to 2048-fold. Robenidine exhibited antimicrobial activity against Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa, in the presence of sub-inhibitory concentrations of either EDTA or PMBN. Robenidine also demonstrated potent antibacterial activity against multidrug-resistant Gram-positive pathogens and all Gram-negative pathogens isolated from cases of canine otitis externa in the presence of EDTA. Robenidine did not demonstrate antibiofilm activity against Gram-positive and Gram-negative bacteria. EDTA facilitated biofilm biomass degradation for both Gram-positives and Gram-negatives. The addition of robenidine to EDTA was not associated with any change in the effect on biofilm biomass degradation. The combination of robenidine with EDTA or PMBN has potential for further exploration and pharmaceutical development, such as incorporation into topical and otic formulations for animal and human use.

Molecular characterisation of methicillin-resistant Staphylococcus pseudintermedius from dogs and the description of their SCCmec elements

In recent years an increasing number of methicillin-resistant S. pseudintermedius (MRSP) has been observed in both, healthy and clinically infected dogs. The aim of the study was the characterisation of MRSP isolates from clinical routine diagnostics of a German laboratory in order to assess the abundancy of resistance genes and SCCmec elements. 97 isolates from 96 dogs were analysed using microarrays detecting resistance genes and SCCmec-associated markers. All isolates harboured mecA and blaZ. Other abundant resistance markers (in >80% of isolates) included aacA-aphD, aphA3 and sat as well as erm(B). Tetracycline resistance genes (tet(K), tet(M)) and cat also were common (in >20%). The vast majority (n = 59) of isolates carried SCCmec III elements. SCCmec IV and V elements were identified in 21 and 15 isolates, respectively. Irregular or pseudo-SCCmec elements were found in 2 isolates. The high degree of uniformity of hybridisation patterns of tested strains suggest that the majority of MRSP infections was caused by one single strain and comparison to previously published reports and sequences suggest that this was the ST71-SCCmec III strain that also predominates elsewhere in Western Europe.

A randomized, controlled, single-blinded, multicenter evaluation of the efficacy and safety of a once weekly two dose otic gel containing florfenicol, terbinafine and betamethasone administered for the treatment of canine otitis externa

Background

Otitis externa is a common problem in small animal practice. Compliance with daily treatment is a major cause of treatment failure. The hypothesis tested is that a novel otic gel applied to the ear canal twice with a one-week interval is as efficacious as a daily otic suspension in the treatment of canine otitis externa. The study included 286 privately owned dogs with otitis externa.

In this single blinded randomized study, enrolled dogs received either an otic gel containing 1% florfenicol, 1% terbinafine and 0.1% betamethasone acetate twice with a one-week interval or a suspension containing hydrocortisone aceponate, miconazole and gentamicin daily for 5 days. Ears were cleaned with saline prior to administration of the first dose of medication. Dogs were evaluated at day (D) 0, 7, 28 and 56 with an otitis index score (OTIS-3), otic culture and cytology, pain and pruritus, and overall response to treatment (owner and investigator evaluation). Outcome measures were improvement of the OTIS-3 and number of dogs in clinical remission at each time point.

Results

OTIS-3 decreased significantly (p < 0.0001) by 63 and 64% for the otic gel and by 63 and 61% for the suspension on D28 and D56 respectively. There was no significant difference between groups at any time point with regard to clinical success, pain, pruritus, overall assessments or otic cytology and culture. The treatment response was considered excellent or good by approximately three quarters of both the clinicians and Owners. Otitis recurrence at D56 was seen in 11% of both groups. Adverse events attributable to the ear medications were not noted.

Conclusions

Administering an otic gel twice at a one-week interval is an effective, safe and convenient way to treat canine otitis externa.

In vitro antimicrobial activity of monensin against common clinical isolates associated with canine otitis externa

Antimicrobial resistance and antimicrobial stewardship are of ever-increasing importance in veterinary medicine. Multidrug-resistant infections of the canine skin and ear continue to emerge, but the use of antibiotic classes of critical importance to human medicine may not represent good antimicrobial stewardship. Repurposing of old drugs that are not used in human medicine is one approach that addresses both these issues. In this study, the minimal inhibitory concentration (MIC) of monensin for 111 bacterial and yeast canine otitis isolates was determined using microdilution methodology according to Clinical Laboratory Standards Institute (CLSI) guidelines. Monensin was effective against all Gram-positive bacteria including the multidrug-resistant staphylococcal strains with MICs ranging from 1 to 4 μg/ml, but lacked antimicrobial activity against Gram-negative bacteria and yeast isolates. Monensin has potential to be incorporated as one of the main components in an otic formulation.

Impact of systemic antimicrobial therapy on mucosal staphylococci in a population of dogs in Northwest England

BACKGROUND

Antimicrobial-resistant bacteria are increasingly isolated from veterinary patients.

OBJECTIVES

To determine risk factors for antimicrobial resistance (AMR) among canine mucosal staphylococci following routine antimicrobial treatment with cefalexin (CFX), clavulanate-amoxicillin (AC), cefovecin (CVN), clindamycin (CD) or a fluoroquinolone (FQ).

ANIMALS

Mucosal swab samples (n = 463) were collected from 127 dogs pre-treatment, immediately, and at one- and three-months post-treatment.

METHODS

Staphylococci were identified phenotypically and biochemically as coagulase negative (CoNS) or coagulase positive (CoPS); CoPS were speciated by nuc gene PCR. Antimicrobial susceptibility was determined using disc diffusion and mecA gene carriage by PCR. Multilevel, multivariable models examined associations between risk factors and presence/absence of CoPS, meticillin resistance (MR), multidrug-resistance (MDR) and fluoroquinolone resistance (FQR).

RESULTS

The percentage of samples with CoNS increased and with CoPS (including S. pseudintermedius) decreased immediately post-treatment with CFX, CVN and CD (P ≤ 0.001) and one month post-treatment with CD (P = 0.003). By three months post-treatment, there was no significant difference compared to pre-treatment samples. Immediately post-treatment with FQs there was significantly increased risk of isolating MRS (P = 0.002), MDR (P = 0.002) or FQR (P = 0.013) staphylococci and of MDR following CFX treatment (P = 0.019). The percentage of samples with AMR staphylococci declined from immediately to three months post-treatment and there was no significant difference between resistance prevalence at one or three months post-treatment for most AMR traits and treatment groups. Exceptions include increased MDR following FQ (P = 0.048) or CFX (P = 0.021), at one and three months post-treatment, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

Systemic antimicrobials impact on mucosal staphylococci. Immediately after therapy, the mucosa may be a reservoir for AMR staphylococci that are a source of mobile genetic elements carrying AMR genes.

Evaluation of Oxacillin and Cefoxitin Disk Diffusion and MIC Breakpoints Established by the Clinical and Laboratory Standards Institute for Detection of mecA-Mediated Oxacillin Resistance in Staphylococcus schleiferi

Staphylococcus schleiferi is a beta-hemolytic, coagulase-variable colonizer of small animals that can cause opportunistic infections in humans. In veterinary isolates, the rate of mecA-mediated oxacillin resistance is significant, with reported resistance rates of >39%. The goal of this study was to evaluate oxacillin and cefoxitin disk diffusion (DD) and MIC breakpoints for detection of mecA-mediated oxacillin resistance in 52 human and 38 veterinary isolates of S. schleiferi Isolates were tested on multiple brands of commercial media and according to Clinical and Laboratory Standards Institute (CLSI) methods. Zone diameters and MIC values were interpreted using CLSI breakpoints (CLSI, Performance Standards for Antimicrobial Susceptibility Testing. M100-S27, 2017) for Staphylococcus aureus/Staphylococcus lugdunensis, coagulase-negative staphylococci (CoNS), and Staphylococcus pseudintermedius Results were compared to those of mecA PCR. Twenty-nine of 90 (32%) isolates were mecA positive. Oxacillin inhibition zone sizes and MICs interpreted by S. pseudintermedius breakpoints reliably differentiated mecA-positive and mecA-negative isolates, with a categorical agreement (CA) of 100% and no very major errors (VMEs) or major errors (MEs) for all media. For cefoxitin DD results interpreted using S. aureus/S. lugdunensis and CoNS breakpoints, CA values were 85% and 75%, respectively, and there were 72% and 64% VMEs, respectively, and 0 MEs. For cefoxitin MICs interpreted using S. aureus/S. lugdunensis breakpoints, CA was 81%, and there were 60% VMEs and no MEs. Our data demonstrate that oxacillin DD or MIC testing methods using the current S. pseudintermedius breakpoints reliably identify mecA-mediated oxacillin resistance in S. schleiferi, while cefoxitin DD and MIC testing methods perform poorly.

Expression and function of protein A in Staphylococcus pseudintermedius

Staphylococcus pseudintermedius is an opportunistic pathogen in dogs and the most frequent cause of canine pyoderma. Protein A, a potent virulence factor in S. aureus is encoded by the spa gene. S. pseudintermedius possesses genes seemingly analogous to spa, but the expression and the characteristics of their products have not been directly determined. The purpose of this study was to test isolates from major clonal groups for the presence of spa gene orthologs, quantitate their expression levels, and to characterize protein A in S. pseudintermedius.  From the data, it was observed that S. pseudintermedius isolates express genes analogous to spa in S. aureus. Isolates representing major clonal populations in the United States and Europe, ST68 and ST71 respectively, bound significantly higher amounts of canine IgG than isolates with other genetic backgrounds, suggesting that these isolates have a higher density of protein A on their surface. Also, canine IgG bound to protein A on S. pseudintermedius via its Fc region similar to protein A from S. aureus. The mRNA profile differed based on the bacterial sequence types and correlated to the density of protein A on the bacterial surface. Protein A was also found to be secreted during the exponential growth phase. Phagocytosis experiments with S. pseudintermedius show that blocking of protein A enhanced phagocytosis in whole blood, neutrophils and in DH82 canine macrophage-like cell line. Taken together, the results demonstrate that S. pseudintermedius produces protein A that shares S. aureus protein A's ability to bind the Fc region of immunoglobulins and may serve as a potential virulence factor by evading the host immune system.

An investigation of methicillin-resistant Staphylococcus pseudintermedius (MRSP) in domestic and shelter dogs in Montenegro (RS-Brazil)

SUMMARY The interaction established between man and their pets has been increasing progressively. The diagnosis of animals carrying methicillin-resistant Staphylococcus pseudintermedius (MRSP) becomes important since positive results for this opportunistic bacteria has been found in humans. The aim of this study was to investigate methicillin-resistant Staphylococcus pseudintermedius (MRSP) in domestic dogs attended in a veterinary clinic and shelter dogs. Anal and nasal swabs from 53 domestic dogs and 46 shelter dogs were collected between the months of August and October of 2015, resulting in 198 samples, which were sent for routine laboratory analysis and subsequently used for this study. Phenotypic tests for bacteria identification and susceptibility to oxacillin were performed for the investigation of MRSP. A total of 23 samples (11.6%) from 21 dogs were positive for S. pseudintermedius, however none of the isolates were MRSP. Nasal and anal swabs had similar positivity and two dogs were carriers of the bacteria in both analyzed sites (anal and nasal). Our results showed a higher positivity for S. pseudintermedius in domestic dogs compared to shelter dogs, as well as indicating the importance of collecting more than one colonization site. This is the first study to perform a comparison among different animal creating sites in Brazil.

Comparison of culture methodology for the detection of methicillin-resistant Staphylococcus pseudintermedius in clinical specimens collected from dogs

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged as a major pathogen in dogs and has been implicated as a hospital-acquired pathogen in veterinary hospitals. We attempted to determine if selective culture methods will detect more MRSP when compared to the traditional culture methods in clinical samples from dogs in Atlantic Canada with a high risk for MRSP infection. Each sample was tested using 4 culture methods: traditional culture; mannitol salt agar with 2 μg/mL of oxacillin (MSAox); enrichment broth (EB) with MSAox; and EB with traditional culture. Detection of penicillin-binding protein 2', via latex agglutination, was used as a confirmatory test for oxacillin resistance. We analyzed 741 samples from 556 dogs between February 2013 and April 2014. The prevalence of MRSP in samples detected by any method was estimated at 13.4% (95% CI: 11.1-16.0%). When the prevalence of MRSP was determined according to culture method, EB with MSAox detected the highest prevalence (11.2% [9.1-13.7%]), followed by EB with traditional (10.8% [8.8-13.2%]), traditional (10.1% [8.1-12.5%]), and MSAox (8.9% [7.1-11.2%]). The prevalence using the traditional culture method did not differ significantly from any of the 3 selective culture methods. Culture with MSAox detected significantly fewer MRSP than either of the EB methods. The addition of EB to current methodology is recommended, particularly for patients considered at high risk for MRSP infection.

Recommendations for approaches to meticillin-resistant staphylococcal infections of small animals: diagnosis, therapeutic considerations and preventative measures.: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology

BACKGROUND

Multiple drug resistance (MDR) in staphylococci, including resistance to the semi-synthetic penicillinase-resistant penicillins such as meticillin, is a problem of global proportions that presents serious challenges to the successful treatment of staphylococcal infections of companion animals.

OBJECTIVES

The objective of this document is to provide harmonized recommendations for the diagnosis, prevention and treatment of meticillin-resistant staphylococcal infections in dogs and cats.

METHODS

The authors served as a Guideline Panel (GP) and reviewed the literature available prior to September 2016. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) provided guidance and oversight for this process. A draft of the document was presented at the 8th World Congress of Veterinary Dermatology (May 2016) and was then made available via the World Wide Web to the member organizations of the WAVD for a period of three months. Comments were solicited and posted to the GP electronically. Responses were incorporated by the GP into the final document.

CONCLUSIONS

Adherence to guidelines for the diagnosis, laboratory reporting, judicious therapy (including restriction of use policies for certain antimicrobial drugs), personal hygiene, and environmental cleaning and disinfection may help to mitigate the progressive development and dissemination of MDR staphylococci.

The in vitro antibacterial activity of incomplete iron salt of polyacrylic acid against Pseudomonas aeruginosa, meticillin-resistant Staphylococcus pseudintermedius and meticillin-resistant S. aureus

BACKGROUND

The incomplete iron salt of polyacrylic acid (IIS-PAA) has been used for its haemostatic, wound healing and antibacterial properties in human patients. IIS-PAA is a water-soluble, acidic, hydrophilic polymer that is active at pH 2.9-4.0.

HYPOTHESES/OBJECTIVES

To evaluate the antibacterial effect of IIS-PAA against Pseudomonas aeruginosa, meticillin-resistant Staphylococcus pseudintermedius (MRSP) and meticillin-resistant S. aureus (MRSA).

METHODS

This was a prospective, nonblinded in vitro study. Sixty canine isolates of P. aeruginosa, MRSP and MRSA were included. Minimum inhibitory concentrations (MICs) of IIS-PAA were determined by agar dilution on Mueller-Hinton agar using testing concentrations ranging from 0.0625-0.4% (raw material 100%) and based on Clinical and Laboratory Standards Institute guidelines.

RESULTS

The median MIC for P. aeruginosa was 0.2% (range 0.2-0.3%), mean 0.2% and standard deviation (SD) of 0.018%. The median MIC for MRSP was 0.05% (0.025-0.1%), mean 0.058% and SD 0.022%, and the median MIC for MRSA was 0.1% (0.00625-0.4%), mean 0.126% and SD 0.080%. There were significant differences in MICs between the three bacteria types with MICs highest for Pseudomonas and lowest for MRSP (all P < 0.0001).

CONCLUSIONS

IIS-PAA had in vitro antibacterial activity against three important bacterial pathogens. Further studies of IIS-PAA are indicated to assess the potential clinical benefit and in vitro studies to investigate the spectrum of anti-bacterial activity and mode of action.

Establishing a canine superficial pyoderma model

AIMS

Pyoderma, predominantly associated with Staphylococcus pseudintermedius, is a common skin infection of dogs that typically requires long-lasting treatments, complicated by increasing antimicrobial resistance. To investigate new treatment strategies, we aimed at establishing a dog model of pyoderma that closely mimics the natural disease.

METHODS AND RESULTS

We inoculated six laboratory beagles with a methicillin-susceptible strain of S. pseudintermedius. One millilitre of approximately 10⁷ , 10⁸ , 10⁹ CFU per ml was topically applied onto clipped and tape stripped area of dog skin, which was then treated with a dermaroller (microneedle size: 500 μm) immediately after administration. Dogs were monitored daily, suspect pustules were cultured for S. pseudintermedius and evaluated by cytological and histopathological methods. After 24 h, all dogs developed papules and pustules at all three bacterial inoculation sites, which worsened over the next 48 h. Cytological samples of all skin lesions revealed neutrophils with intracellular cocci. Histopathology confirmed subcorneal neutrophilic pustular dermatitis with intralesional cocci and acantholytic keratinocytes, consistent with superficial pyoderma. Staphylococcus pseudintermedius was isolated from pustules of all dogs and confirmed to be the inoculating strain. The results were replicated in all dogs after a wash out period of 6 weeks.

CONCLUSIONS

These data demonstrate the feasibility of establishing a dog model of pyoderma.

SIGNIFICANCE AND IMPACT OF THE STUDY

The new model can be used to evaluate novel prevention and treatment options for canine pyoderma.

Clinical features, cytology and bacterial culture results in dogs with and without cheilitis and comparison of three sampling techniques

BACKGROUND

Cheilitis is a common presentation in dogs associated with a variety of skin diseases and often complicated by microbial infections.

OBJECTIVES

To describe and compare clinical and cytological features and bacterial culture results from the lower lips of dogs with cheilitis (as compared to healthy controls), and to evaluate three cytology sampling techniques for their abilities to differentiate between the groups.

ANIMALS

Fifty six dogs with cheilitis and 54 controls.

METHODS

Anatomy and clinical signs of the lower lip were recorded. Cytology samples taken by tape strip, direct impression and swabs rolled over skin were scored semiquantitatively for microorganisms, inflammatory cells and keratinocytes. Cytology scores were correlated with semiquantitative bacterial culture scores.

RESULTS

Pure breeds, frequency of lip folds and all cytology scores except keratinocytes were higher in dogs with cheilitis than in controls, but a substantial overlap was seen in all microorganisms between the groups. Hypersensitivity disorders were diagnosed in 40 of 56 dogs with cheilitis. The tape strip technique yielded the greatest differences between groups. Bacterial growth was reported in 100% of dogs with cheilitis and in 93% of the controls. Pathogens such as Staphylococcus pseudintermedius, Escherichia coli and Pseudomonas spp were found more frequently in dogs with cheilitis. Cytology and bacterial culture were poorly correlated.

CONCLUSION

Cheilitis was associated with primary hypersensitivity disorders and the presence of a lip fold was a predisposing factor. Results of aerobic culture were similar to prior studies on pyoderma of other body sites, except for higher rates of Pseudomonas spp. isolation.

First report of a mecA-positive multidrug-resistant Staphylococcus pseudintermedius isolated from a dog in New Zealand

CASE HISTORY

A 14-year-old neutered male Sealyham terrier was referred for assessment of a persistent pyoderma. It had experienced numerous episodes of dermatitis involving pododermatitis, pyoderma and otitis over the previous 6 years.

CLINICAL FINDINGS

Superficial, focally deep and mucocutaneous pyoderma were present, with yellow mucoid exudate on both nares and the lower lips crusted with haemopurulent exudate. Epidermal collarettes were present on the dorsal and lateral trunk. There were peri-anal crusts and mild erythema was present on the concave aspect of both pinnae.

MICROBIOLOGICAL FINDINGS

Culture and microbiological testing identified Staphylococcus pseudintermedius as the infecting organism. Kirby-Bauer disc susceptibility testing revealed the isolate was resistant to numerous antimicrobials including oxacillin. PCR testing of the isolate identified the presence of the mecA gene which confers resistance to β-lactam antimicrobials. Pulsed field gel electrophoresis typing suggested the isolate was not related to the methicillin-resistant S. pseudintermedius that had been reported to be associated with canine infections in Western Australia.

DIAGNOSIS

Superficial, deep and mucus membrane pyoderma associated with a multi-drug resistant S. pseudintermedius.

CLINICAL RELEVANCE

This is the first recorded case of canine pyoderma involving methicillin-resistant multidrug-resistant S. pseudintermedius in New Zealand. Treatment of such cases is difficult because the number of effective and available antimicrobials is limited. This finding should raise the awareness of the veterinary and medical professions to the presence of such organisms in New Zealand and stimulate a discussion about possible biosecurity barriers, treatment strategies and prevention of zoonotic and nosocomial infections.

Prior antibacterial drug exposure in dogs with meticillin-resistant Staphylococcus pseudintermedius (MRSP) pyoderma

BACKGROUND

The emergence of meticillin-resistant Staphylococcus pseudintermedius (MRSP) has become a significant animal health problem. Recent studies have indicated that previous antibacterial drug exposure is a factor in acquisition of meticillin-resistant strains of staphylococci.

HYPOTHESIS/OBJECTIVES

The purpose of this study was to identify factors associated with prior antimicrobial drug use and MRSP pyoderma in dogs presented to a veterinary teaching hospital.

ANIMALS

Dogs diagnosed with pyoderma associated with MRSP (n = 53) or meticillin-sensitive S. pseudintermedius (MSSP; n = 45).

METHODS

The medical records of dogs diagnosed with pyoderma associated with isolation of S. pseudintermedius between January 2006 and November 2012 were reviewed. All cases with a complete twelve month to 3 yr drug history prior to the diagnosis were included.

RESULTS

Fifty two of 53 (98%) MRSP cases and 42 of 45 (93%) MSSP cases had received at least one course of antibacterial drug prior to diagnosis. The total number of antibacterial drug prescriptions provided to pet owners and the variety of antibacterial drug classes represented were higher for cases with MRSP than for cases with MSSP (P < 0.0001 and P = 0.009, respectively). More cases with MRSP (98%) received beta-lactam drugs than those with MSSP (82%; P = 0.007) and the proportion of MRSP cases that had received concurrent immunomodulatory therapy was higher (62% versus 42%; P = 0.048).

CONCLUSIONS AND CLINICAL IMPORTANCE

These results suggest that the total number of antibacterial drug prescriptions, exposure to multiple drug classes (beta-lactams in particular) and concurrent immunomodulatory therapy may be associated with increased risk for acquisition of MRSP.

Longitudinal Evaluation of the Skin Microbiome and Association with Microenvironment and Treatment in Canine Atopic Dermatitis

Host-microbe interactions may play a fundamental role in the pathogenesis of atopic dermatitis, a chronic relapsing inflammatory skin disorder characterized by universal colonization with Staphylococcus species. To examine the relationship between epidermal barrier function and the cutaneous microbiota in atopic dermatitis, this study used a spontaneous model of canine atopic dermatitis. In a cohort of 14 dogs with canine atopic dermatitis, the skin microbiota were longitudinally evaluated with parallel assessment of skin barrier function at disease flare, during antimicrobial therapy, and post-therapy. Sequencing of the bacterial 16S ribosomal RNA gene showed decreased bacterial diversity and increased proportions of Staphylococcus (S. pseudintermedius in particular) and Corynebacterium species compared with a cohort of healthy control dogs (n = 16). Treatment restored bacterial diversity with decreased proportions of Staphylococcus species, concurrent with decreased canine atopic dermatitis severity. Skin barrier function, as measured by corneometry, pH, and transepidermal water loss also normalized with treatment. Bacterial diversity correlated with transepidermal water loss and pH level but not with corneometry results. These findings provide insights into the relationship between the cutaneous microbiome and skin barrier function in atopic dermatitis, show the impact of antimicrobial therapy on the skin microbiome, and highlight the utility of canine atopic dermatitis as a spontaneous nonrodent model of atopic dermatitis.

Evaluation of Bacterial Contamination of Clipper Blades in Small Animal Private Practice

Nosocomial infections are a growing concern in veterinary hospitals, and identifying fomites is imperative to reducing the risk of pathogen transmission. In veterinary medicine, shaving of hair is necessary prior to many procedures. Contaminated clipper blades have been cited as potential fomites involved in the transmission of pathogens in veterinary and human medicine. The primary goal of this study was to evaluate bacterial contamination of clipper blades in veterinary practices. A secondary goal was to assess whether there was an association between bacterial contamination of clipper blades and clipper blade cleaning solutions, clipper blade cleaning protocols, clipper blade storage, and type of practice. Sixty clipper blades from 60 different practices were cultured. Information regarding blade cleaning solutions, protocols, and storage was collected from each practice. Fifty-one percent (31/60) of clipper blades sampled were contaminated with bacteria. Category of cleaning solutions had a significant association with bacterial contamination (P < 0.02). Cleaning frequency (P = 0.55), storage location (P = 0.26), and practice type (P = 0.06) had no significant association with bacterial contamination. This study documented bacterial contamination of clipper blades in veterinary practices, and clipper blades should be considered potential fomites.

Evaluation of Oxacillin and Cefoxitin Disk and MIC Breakpoints for Prediction of Methicillin Resistance in Human and Veterinary Isolates of Staphylococcus intermedius Group

Staphylococcus pseudintermedius is a coagulase-positive species that colonizes the nares and anal mucosa of healthy dogs and cats. Human infections with S. pseudintermedius range in severity from bite wounds and rhinosinusitis to endocarditis; historically, these infections were thought to be uncommon, but new laboratory methods suggest that their true incidence is underreported. Oxacillin and cefoxitin disk and MIC tests were evaluated for the detection of mecA- or mecC-mediated methicillin resistance in 115 human and animal isolates of the Staphylococcus intermedius group (SIG), including 111 Staphylococcus pseudintermediusand 4 Staphylococcus delphini isolates, 37 of which were mecA positive. The disk and MIC breakpoints evaluated included the Clinical and Laboratory Standards Institute (CLSI) M100-S25 Staphylococcus aureus/Staphylococcus lugdunensis oxacillin MIC breakpoints and cefoxitin disk and MIC breakpoints, the CLSI M100-S25 coagulase-negative Staphylococcus (CoNS) oxacillin MIC breakpoint and cefoxitin disk breakpoint, the CLSI VET01-S2 S. pseudintermedius oxacillin MIC and disk breakpoints, and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) S. pseudintermedius cefoxitin disk breakpoint. The oxacillin results interpreted by the VET01-S2 (disk and MIC) and M100-S25 CoNS (MIC) breakpoints agreed with the results of mecA/mecC PCR for all isolates, with the exception of one false-resistant result (1.3% of mecA/mecC PCR-negative isolates). In contrast, cefoxitin tests performed poorly, ranging from 3 to 89% false susceptibility (very major errors) and 0 to 48% false resistance (major errors). BD Phoenix, bioMérieux Vitek 2, and Beckman Coulter MicroScan commercial automated susceptibility test panel oxacillin MIC results were also evaluated and demonstrated >95% categorical agreement with mecA/mecC PCR results if interpreted by using the M100-S25 CoNS breakpoint. The Alere penicillin-binding protein 2a test accurately detected all mecA-positive isolates, although for four isolates, cefoxitin induction was required prior to testing. These data demonstrate that the cefoxitin surrogate test does not reliably detect the presence of mecA in S. pseudintermedius isolates and that laboratories should perform oxacillin disk or MIC tests of these isolates when they are encountered.

Changes in the Population of Methicillin-Resistant Staphylococcus pseudintermedius and Dissemination of Antimicrobial-Resistant Phenotypes in the Netherlands

Methicillin-resistant Staphylococcus pseudintermedius (MRSP), which is often multidrug resistant (MDR), has recently emerged as a threat to canine health worldwide. Knowledge of the temporal distribution of specific MRSP lineages, their antimicrobial resistance phenotypes, and their association with clinical conditions may help us to understand the emergence and spread of MRSP in dogs. The aim of this study was to determine the yearly proportions of MRSP lineages and their antimicrobial-resistant phenotypes in the Netherlands and to examine possible associations with clinical conditions. MRSP was first isolated from a canine specimen submitted for diagnostics to the Faculty of Veterinary Medicine of Utrecht University in 2004. The annual cumulative incidence of MRSP among S. pseudintermedius increased from 0.9% in 2004 to 7% in 2013. MRSP was significantly associated with pyoderma and, to a lesser extent, with wound infections and otitis externa. Multilocus sequence typing (MLST) of 478 MRSP isolates yielded 39 sequence types (ST) belonging to 4 clonal complexes (CC) and 15 singletons. CC71 was the dominant lineage that emerged since 2004, and CC258, CC45, and several unlinked isolates became more frequent during the following years. All but two strains conferred an MDR phenotype, but strains belonging to CC258 or singletons were less resistant. In conclusion, our study showed that MDR CC71 emerged as the dominant lineage from 2004 and onward and that less-resistant lineages were partly replacing CC71.

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) from healthy dogs in Norway - occurrence, genotypes and comparison to clinical MRSP

The aim of the study was to investigate the occurrence of methicillin‐resistant Staphylococcus pseudintermedius (MRSP) in healthy dogs and further to determine genetic relatedness between carrier isolates and clinical MRSP from dogs in Norway. A total of 189 healthy dogs visiting ten veterinary clinics were screened for MRSP during the period February to April 2013. Carrier isolates were susceptibility tested with disk diffusion and genotyped using multilocus sequence typing (MLST) and pulsed‐field gel electrophoresis (PFGE). Forty‐nine clinical MRSP were characterized for comparison. These isolates were collected from July 2008 to April 2013 and represent all MRSP index isolates from each MRSP‐positive dog detected in Norway until April 2013. Geographical distribution of all MRSP cases was investigated using the ArcGIS 9.3 Software. MRSP was detected from five (2.6%) healthy dogs, sampled at three different clinics. The isolates grouped into three sequence types (STs): ST252 (two isolates), ST71 (two isolates) and ST306 (one isolate). MRSP from dogs sampled at the same animal clinic belonged to the same ST and produced identical PFGE pattern. The 49 clinical MRSP grouped into 15 STs; ST258 (n = 17), ST71 (n = 10), and ST305 (n = 4) were the most prevalent. The MRSP carrier isolates were genetically related to MRSP variants from dogs with infections as ST306 (from a carrier) is related to ST258. MRSP ST252, found in two carriers, was also present among the clinical MRSP isolates. Altogether the MRSP isolates were genetically diverse and MRSP of other lineages than ST71 continues to disseminate in Norway. Susceptibility testing showed that MRSP isolates of the ST71 lineage were the most multiresistant. Our study showed that MRSP could be detected in healthy dogs without infections and with no recent history of antimicrobial therapy stressing the need for future monitoring, infection control and prudent use of antimicrobial agents.

Direct Repeat Unit (dru) Typing of Methicillin-Resistant Staphylococcus pseudintermedius from Dogs and Cats

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged in a remarkable manner as an important problem in dogs and cats. However, limited molecular epidemiological information is available. The aims of this study were to apply direct repeat unit (dru) typing in a large collection of well-characterized MRSP isolates and to use dru typing to analyze a collection of previously uncharacterized MRSP isolates. Two collections of MRSP isolates from dogs and cats were included in this study. The first collection comprised 115 well-characterized MRSP isolates from North America and Europe. The data for these isolates included multilocus sequence typing (MLST) and staphylococcal protein A gene (spa) typing results as well as SmaI macrorestriction patterns after pulsed-field gel electrophoresis (PFGE). The second collection was a convenience sample of 360 isolates from North America. The dru region was amplified by PCR, sequenced, and analyzed. For the first collection, the discriminatory indices of the typing methods were calculated. All isolates were successfully dru typed. The discriminatory power for dru typing (D = 0.423) was comparable to that of spa typing (D = 0.445) and of MLST (D = 0.417) in the first collection. Occasionally, dru typing was able to further discriminate between isolates that shared the same spa type. Among all 475 isolates, 26 different dru types were identified, with 2 predominant types (dt9a and dt11a) among 349 (73.4%) isolates. The results of this study underline that dru typing is a useful tool for MRSP typing, being an objective, standardized, sequence-based method that is relatively cost-efficient and easy to perform.